U.S. patent number 6,299,300 [Application Number 09/113,082] was granted by the patent office on 2001-10-09 for micro electro-mechanical system for ejection of fluids.
This patent grant is currently assigned to Silverbrook Research Pty Ltd. Invention is credited to Kia Silverbrook.
United States Patent |
6,299,300 |
Silverbrook |
October 9, 2001 |
Micro electro-mechanical system for ejection of fluids
Abstract
An integral structure within an MEMS device is used to filter
out foreign bodies in a fluid supply. The system is initially
constructed in a large planar form, and the effect of impurities is
reduced by fabricating an integral grill structure in the path of
the flow of the liquid so as to filter foreign, bodies in the
liquid. Ideally used in an ink jet printing system, the grill forms
one wall of a nozzle chamber for filtering ink entering the nozzle
chamber to be ejected from the nozzle chamber. The filter can be
constructed from nitride as is the nozzle chamber.
Inventors: |
Silverbrook; Kia (Sydney,
AU) |
Assignee: |
Silverbrook Research Pty Ltd
(Balmain, AU)
|
Family
ID: |
25645488 |
Appl.
No.: |
09/113,082 |
Filed: |
July 10, 1998 |
Foreign Application Priority Data
|
|
|
|
|
Jul 15, 1997 [AU] |
|
|
PO7991 |
Jul 15, 1997 [AU] |
|
|
PO8011 |
|
Current U.S.
Class: |
347/93;
348/E5.024; 348/E5.055 |
Current CPC
Class: |
B41J
2/14314 (20130101); B41J 2/14427 (20130101); B41J
2/1626 (20130101); B41J 2/1628 (20130101); B41J
2/1629 (20130101); B41J 2/1631 (20130101); B41J
2/1632 (20130101); B41J 2/1639 (20130101); B41J
2/1642 (20130101); B41J 2/1643 (20130101); B41J
2/1645 (20130101); B41J 2/1646 (20130101); B41J
2/1648 (20130101); B41J 2/17596 (20130101); B82Y
30/00 (20130101); G06K 1/121 (20130101); G06K
7/14 (20130101); G06K 7/1417 (20130101); G06K
19/06037 (20130101); G11C 11/56 (20130101); H04N
5/225 (20130101); H04N 5/2628 (20130101); B41J
2/16585 (20130101); B41J 2002/041 (20130101) |
Current International
Class: |
B41J
2/14 (20060101); B41J 11/70 (20060101); B41J
15/04 (20060101); B41J 2/16 (20060101); B42D
15/10 (20060101); B41J 2/175 (20060101); B41J
3/42 (20060101); B41J 11/00 (20060101); G06F
1/16 (20060101); G06K 1/12 (20060101); G06K
1/00 (20060101); G07F 7/12 (20060101); G06K
19/073 (20060101); G07F 7/08 (20060101); G11C
11/56 (20060101); G06K 7/14 (20060101); G06K
19/06 (20060101); H04N 5/262 (20060101); H04N
5/225 (20060101); H04N 1/32 (20060101); H04N
1/21 (20060101); B41J 2/165 (20060101); H04N
1/00 (20060101); B41J 002/175 () |
Field of
Search: |
;347/93,86,54,56,40 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Le; N.
Assistant Examiner: Nghiem; Michael
Claims
What is claimed is:
1. A monolithic micro-mechanical system for the ejection of fluid,
said system comprising:
a wafer substrate;
a series of nozzle chambers formed on said wafer substrate, each
nozzle chamber comprising an ink ejection port formed in a first
wall of said each nozzle for, in use, ejection of the ink, and each
nozzle chamber further comprising grill apertures formed in a
second wall of said each nozzle chamber, said grill apertures being
oriented substantially perpendicularly with respect to said wafer
substrate; and
a fluid supply for supplying fluid to each of said nozzle chambers,
said spaced apart grill apertures forming filters between said
nozzle chambers and said fluid supply.
2. A system as claimed in claim 1 wherein said nozzle chambers each
include a thermal bend actuator attached at a first end to said
substrate and having a second moveable end located away from said
spaced apart poles, said moveable end being actuable to cause the
ejection of said ink from said nozzle chambers, said grill
apertures being formed in said second wall adjacent to the
attachment of said actuator to said substrate.
3. A system as claimed in claim 1, wherein each nozzle chamber
comprises a series of spaced apart poles formed in the s econd wall
of said each nozzle chamber defining said grill apertures, the
poles being oriented substantially perpendicularly with respect to
the substrate.
4. A system as claimed in claim 3 wherein said poles a re formed
from silicon nitride.
5. A system as claimed in claim 1, wherein said nozzle chambers are
formed by a deposition and etching process carried out on said
wafer substrate.
6. A monolithic micro-mechanical system for the ejection of fluid,
said system comprising:
a wafer substrate;
a series of nozzle chambers formed on said wafer substrate, each
nozzle chamber comprising a nozzle aperture formed in a first wall
of said each nozzle chamber for, in use, ejection of the fluid, and
each nozzle chamber further comprising grill apertures formed in a
second wall of said each nozzle chamber;
said grill apertures being of substantially uniform cross-section
along a thickness of the second wall; and
a fluid supply for supplying fluid to each of said nozzle chambers,
said grill apertures forming a filter between said nozzle chambers
and said fluid supply.
7. A system as claimed in claim 6, wherein a thickness of said
second wall is approximately five microns thick.
8. A monolithic micro-mechanical system for the ejection of fluid,
said system comprising a wafer substrate;
a number of nozzle chamber side walls and roof walls formed on said
wafer substrate by deposition and etching techniques, to define a
plurality of nozzle chambers with an ejection port defined in each
roof wall, and the nozzle chamber side walls and the roof walls
defining an inlet to each nozzle chamber; and
a plurality of actuators, each actuator being positioned within a
respective nozzle chamber to eject ink from the respective ejection
ports, wherein a plurality of elongate poles are arranged in a
spaced, side-by-side manner, within each inlet to define a grill
positioned within the inlet, the poles extending substantially
orthogonally with respect to the wafer substrate.
9. A system as claimed in claim 8, in which the poles within each
inlet are configured to pinch the thermal actuator to the wafer
substrate to decrease the likelihood of the actuator becoming
separated from the wafer substrate.
10. A system as claimed in claim 8, in which the nozzle chamber
side walls, roof walls and poles are of silicon nitride.
11. A monolithic micro-mechanical system for the ejection of fluid,
said system comprising
a wafer substrate;
a number of nozzle chamber side walls and roof walls formed on said
wafer substrate by deposition and etching techniques, to define a
plurality of nozzle chambers with an ejection port defined in each
roof wall, and the nozzle chamber side walls and the roof walls
defining an inlet to each nozzle chamber; and
a plurality of actuators, each actuator being positioned within a
respective nozzle chamber to eject ink from the respective ejection
ports, wherein a plurality of elongate poles are arranged in a
spaced, side-by-side manner, within each inlet to define a grill
positioned within the inlet, the poles extending substantially
orthogonally with respect to the wafer substrate;
further wherein the system includes three ink supply channels and
the nozzle chambers are divided into three sets of two rows of
nozzle chambers, each set of nozzle chambers being in fluid
communication with one ink supply channel, so that a differently
colored ink can be supplied to each set of nozzle chambers, via the
respective ink supply channels.
Description
CROSS REFERENCES TO RELATED APPLICATIONS
The following Australian provisional patent applications are hereby
incorporated by cross-reference. For the purposes of location and
identification, US patent applications identified by their US
patent application serial numbers (USSN) are listed alongside the
Australian applications from which the US patent applications claim
the right of priority.
U.S. Pat. No./ PATENT APPLICATION (CLAIMING CROSS-REFERENCED RIGHT
OF PRIORITY AUSTRALIAN FROM AUSTRALIAN PROVISIONAL PATENT
PROVISIONAL APPLICATION NO. APPLICATION) DOCKET NO. PO7991
09/113,060 ART01 PO8505 09/113,070 ART02 PO7988 09/113,073 ART03
PO9395 09/112,748 ART04 PO8017 09/112,747 ART06 PO8014 09/112,776
ART07 PO8025 09/112,750 ART08 PO8032 09/112,746 ART09 PO7999
09/112,743 ART10 PO7998 09/112,742 ART11 PO8031 09/112,741 ART12
PO8030 09/112,740 ART13 PO7997 09/112,739 ART15 PO7979 09/113,053
ART16 PO8015 09/112,738 ART17 PO7978 09/113,067 ART18 PO7982
09/113,063 ART19 PO7989 09/113,069 ART20 PO8019 09/112,744 ART21
PO7980 09/113,058 ART22 PO8018 09/112,777 ART24 PO7938 09/113,224
ART25 PO8016 09/112,804 ART26 PO8024 09/112,805 ART27 PO7940
09/113,072 ART28 PO7939 09/112,785 ART29 PO8501 09/112,797 ART30
PO8500 09/112,796 ART31 PO7987 09/113,071 ART32 PO8022 09/112,824
ART33 PO8497 09/113,090 ART34 PO8020 09/112,823 ART38 PO8023
09/113,222 ART39 PO8504 09/112,786 ART42 PO8000 09/113,051 ART43
PO7977 09/112,782 ART44 PO7934 09/113,056 ART45 PO7990 09/113,059
ART46 PO8499 09/113,091 ART47 PO8502 09/112,753 ART48 PO7981
09/113,055 ART50 PO7986 09/113,057 ART51 PO7983 09/113,054 ART52
PO8026 09/112,752 ART53 PO8027 09/112,759 ART54 PO8028 09/112,757
ART56 PO9394 09/112,758 ART57 PO9396 09/113,107 ART58 PO9397
09/112,829 ART59 PO9398 09/112,792 ART60 PO9399 6,106,147 ART61
PO9400 09/112,790 ART62 PO9401 09/112,789 ART63 PO9402 09/112,788
ART64 PO9403 09/112,795 ART65 PO9405 09/112,749 ART66 PP0959
09/112,784 ART68 PP1397 09/112,783 ART69 PP2370 09/112,781 DOT01
PP2371 09/113,052 DOT02 PO8003 09/112,834 Fluid01 PO8005 09/113,103
Fluid02 PO9404 09/113,101 Fluid03 PO8066 09/112,751 IJ01 PO8072
09/112,787 IJ02 PO8040 09/112,802 IJ03 PO8071 09/112,803 IJ04
PO8047 09/113,097 IJ05 PO8035 09/113,099 IJ06 PO8044 09/113,084
IJ07 PO8063 09/113,066 IJ08 PO8057 09/112,778 IJ09 PO8056
09/112,779 IJ10 PO8069 09/113,077 IJ11 PO8049 09/113,061 IJ12
PO8036 09/112,818 IJ13 PO8048 09/112,816 IJ14 PO8070 09/112,772
IJ15 PO8067 09/112,819 IJ16 PO8001 09/112,815 IJ17 PO8038
09/113,096 IJ18 PO8033 09/113,068 IJ19 PO8002 09/113,095 IJ20
PO8068 09/112,808 IJ21 PO8062 09/112,809 IJ22 PO8034 09/112,780
IJ23 PO8039 09/113,083 IJ24 PO8041 09/113,121 IJ25 PO8004
09/113,122 IJ26 PO8037 09/112,793 IJ27 PO8043 09/112,794 IJ28
PO8042 09/113,128 IJ29 PO8064 09/113,127 IJ30 PO9389 09/112,756
IJ31 PO9391 09/112,755 IJ32 PP0888 09/112,754 IJ33 PP0891
09/112,811 IJ34 PP0890 09/112,812 IJ35 PP0873 09/112,813 IJ36
PP0993 09/112,814 IJ37 PP0890 09/112,764 IJ38 PP1398 09/112,765
IJ39 PP2592 09/112,767 IJ40 PP2593 09/112,768 IJ41 PP3991
09/112,807 IJ42 PP3987 09/112,806 IJ43 PP3985 09/112,820 IJ44
PP3983 09/112,821 IJ45 PO7935 09/112,822 IJM01 PO7936 09/112,825
IJM02 PO7937 09/112,826 IJM03 PO8061 09/112,827 IJM04 PO8054
09/112,828 IJM05 PO8065 6,071,750 IJM06 PO8055 09/113,108 IJM07
PO8053 09/113,109 IJM08 PO8078 09/113,123 IJM09 PO7933 09/113,114
IJM10 PO7950 09/113,115 IJM11 PO7949 09/113,129 IJM12 PO8060
09/113,124 IJM13 PO8059 09/113,125 IJM14 PO8073 09/113,126 IJM15
PO8076 09/113,119 IJM16 PO8075 09/113,120 IJM17 PO8079 09/113,221
IJM18 PO8050 09/113,116 IJM19 PO8052 09/113,118 IJM20 PO7948
09/113,117 IJM21 PO7951 09/113,113 IJM22 PO8074 09/113,130 IJM23
PO7941 09/113,110 IJM24 PO8077 09/113,112 IJM25 PO8058 09/113,087
IJM26 PO8051 09/113,074 IJM27 PO8045 6,111,754 IJM28 PO7952
09/113,088 IJM29 PO8046 09/112,771 IJM30 PO9390 09/112,769 IJM31
PO9392 09/112,770 IJM32 PP0889 09/112,798 IJM35 PP0887 09/112,801
IJM36 PP0882 09/112,800 IJM37 PP0874 09/112,799 IJM38 PP1396
09/113,098 IJM39 PP3989 09/112,833 IJM40 PP2591 09/112,832 IJM41
PP3990 09/112,831 IJM42 PP3986 09/112,830 IJM43 PP3984 09/112,836
IJM44 PP3982 09/112,835 IJM45 PP0895 09/113,102 IR01 PP0870
09/113,106 IR02 PP0869 09/113,105 IR04 PP0887 09/113,104 IR05
PP0885 09/112,810 IR06 PP0884 09/112,766 IR10 PP0886 09/113,085
IR12 PP0871 09/113,086 IR13 PP0876 09/113,094 IR14 PP0877
09/112,760 IR16 PP0878 09/112,773 IR17 PP0879 09/112,774 IR18
PP0883 09/112,775 IR19 PP0880 09/112,745 IR20 PP0881 09/113,092
IR21 PO8006 6,087,638 MEMS02 PO8007 09/113,093 MEMS03 PO8008
09/113,062 MEMS04 PO8010 6,041,600 MEMS05 PO8011 09/113,082 MEMS06
PO7947 6,067,797 MEMS07 PO7944 09/113,080 MEMS09 PO7946 6,044,646
MEMS10 PO9393 09/113,065 MEMS11 PP0875 09/113,078 MEMS12 PP0894
09/113,075 MEMS13
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
FIELD OF THE INVENTION
The present invention relates to a micron electro-mechanical system
for the ejection of fluids.
BACKGROUND OF THE INVENTION
In micro-electro mechanical systems (MEMS) it is often necessary to
manipulate a fluid. The manipulation of a fluid can result in a
clogging of a MEMS system, especially when the fluid contains
contaminating bodies which clog fluid passage ways.
SUMMARY OF THE INVENTION
It is an object of the present invention to an integral structure
with a MEMS device to filter out foreign bodies in an ink
supply.
In accordance with a first aspect of the present invention there is
provided a micro-electro mechanical system for controlling the flow
of a liquid, this system being constructed in a planar form. The
effect of impurities in the liquid is substantially removed by
providing an integral grill structure in the path of the flow of
the liquid. This serves to filter foreign bodies in the liquid.
Preferably, the micro-electro mechanical system comprises an ink
jet printing system and the grill forms one wall of a nozzle
chamber for filtering ink entering the nozzle chamber. Further, the
filter comprises substantially nitride.
BRIEF DESCRIPTION OF THE DRAWINGS
Notwithstanding any other forms which may fall within the scope of
the present invention, preferred forms of the invention will now be
described, by way of example only, with reference to the
accompanying drawings in which:
FIG. 1 is a schematic cross-sectional view of a single ink jet
nozzle constructed in accordance with the preferred embodiment.
FIG. 2 is a schematic cross-sectional view of a single ink jet
nozzle constructed in accordance with the preferred embodiment,
with the thermal actuator in its activated state.
FIG. 3 is a schematic diagram of the conductive layer utilized in
the thermal actuator of the ink jet nozzle constructed in
accordance with the preferred embodiment.
FIG. 4 is a close up perspective view of portion A of FIG. 3.
FIG. 5 is a cross-sectional schematic diagram illustrating the
construction of a corrugated conductive layer in accordance with
the preferred embodiment of the present invention.
FIG. 6 is a schematic cross-sectional diagram illustrating the
development of a resist material through a half-toned mask utilized
in the fabrication of a single ink jet nozzle in accordance with
the preferred embodiment.
FIG. 7 is an exploded perspective view illustrating the
construction of a single ink jet nozzle in accordance with the
preferred embodiment.
FIG. 8 is a perspective view of a portion of an ink jet printhead
having ink jet nozzles in accordance with the preferred
embodiment.
DESCRIPTION OF PREFERRED AND OTHER EMBODIMENTS
The preferred embodiment of the present invention will be discussed
with reference to a fluid system which comprises an ink jet
printing device wherein it is required to filter the ink supply so
as to ensure the continual operation of the ink jet printer. The
present invention should not necessarily be restricted to the field
of ink jet printing, as will be readily evident.
In the preferred embodiment, there is provided an ink jet printer
having ink ejection nozzles from which ink is ejected with the ink
ejection being actuated by means of a thermal actuator which
includes a "corrugated" copper heating element encased in a
polytetrafluoroethylene (PTFE) layer.
Turning now to FIG. 1, there is illustrated a cross-sectional view
of a single ink jet nozzle 10 in accordance with the present
embodiment. The ink jet nozzle 10 includes an ink ejection port 11
for the ejection of ink from a chamber 12 by the actuation of a
thermal paddle actuator 13. The thermal paddle actuator 13
comprises an inner copper heating portion 14 and a planar portion
15 which are encased in an outer PTFE layer 16. The outer PTFE
layer 16 has an extremely high coefficient of thermal expansion
(approximately 770.times.10.sup.-6, or around 380 times that of
silicon). The PTFE layer 16 is also highly hydrophobic which
results in an air bubble 17 being formed under the thermal actuator
13 due to out-gassing etc. The top PTFE layer is treated so as to
make it hydrophilic. The heating portion 14 is also formed within
the lower portion of the actuator 13.
The heater 14 is connected at ends 20,21 (see also FIG. 7) to a
lower CMOS drive layer 18 containing drive circuitry (not shown).
For the purposes of actuation of the actuator 13, a current is
passed through the copper heating portion 14 which heats the bottom
surface of the actuator 13. Turning now to FIG. 2, the bottom
surface of the actuator 13, in contact with air bubble 17 remains
heated while any top surface heating is carried away by the
exposure of the top surface of the actuator 13 to the ink within
the chamber 12. Hence, the bottom PTFE layer expands more rapidly
resulting in a general rapid bending upwards of the actuator 13 (as
illustrated in FIG. 2) which consequentially causes the ejection of
ink from the ink ejection port 11. An air inlet channel 28 is
formed between two nitride layers 42, 26 such that air is free to
flow in the direction of an arrow 29 along a channel 28 and through
holes 25, in accordance with any fluctuating pressure influences.
The air flow acts to reduce the vacuum on the back surface of
actuator 13 during operation. As a result less energy is required
for the movement of the actuator 13.
The actuator 13 can be deactivated by turning off the current to
the heating portion 14. This will result in a return of the
actuator 13 to its rest position.
The thermal actuator 13 includes a number of significant features.
In FIG. 3 there is illustrated a schematic diagram of the
conductive layer of the thermal actuator 13. The conductive layer
defines the planar portion 15, which can be constructed from the
same material as the heating portion 14 copper, and which defines a
series of holes 23. The holes 23 are provided for interconnecting
layers of PTFE both above and below the planar portion 15 so as to
resist any movement of the PTFE layers relative to the planar
portion 15 and thereby reducing any opportunities for the
delamination of the PTFE and copper layers.
Turning to FIG. 4, there is illustrated a close up view of the
heating portion 14 illustrating corrugations 22 of the heating
portion 14 within the PTFE. The corrugations 22 of the heater 14
allow for a rapid heating of portions of a bottom layer surrounding
the corrugations 22. Any resistive heater which is based upon
applying a current to heat an object will result in a rapid,
substantially uniform elevation in temperature of the outer surface
of the current carrying conductor. The surrounding PTFE volume is
therefore heated by means of thermal conduction from the heating
portion 14. This thermal conduction is known to proceed, to a first
approximation, at a substantially linear rate with respect to
distance from a resistive element. By utilizing the corrugations,
the bottom surface of the actuator 13 is more rapidly heated as, on
average, a greater volume of the bottom PTFE surface is closer to a
portion of the resistive element. Therefore a rapid actuation of
the actuator 13 results. Further, the corrugation 22 also assist in
resisting any delamination of the copper and PTFE layer.
Turning now to FIG. 5, the corrugated resistive element can be
formed by depositing a resist layer 50 on top of the first PTFE
layer 51. The resist layer 50 is exposed utilizing a mask 52 having
a half-tone pattern delineating the corrugations. After development
the resist 50 contains the corrugation pattern. The resist layer 50
and the PTFE layer 51 are then etched utilizing an etchant that
erodes the resist layer 50 at substantially the same rate as the
PTFE layer 51. This transfers the corrugated pattern into the PTFE
layer 51. Turning to FIG. 6, on top of the corrugated PTFE layer 51
is deposited the heating portion 14 which takes on a corrugated
form in accordance with its under layer. The heating portion layer
14 is then etched in a serpentine or concertina form. Subsequently,
a further PTFE layer 53 is deposited on top of the heating portion
14 so as to form the top layer of the thermal actuator 13. Finally,
the second PTFE layer 52 is planarized to form the top surface of
the thermal actuator 13 (FIG. 1).
Returning again now to FIG. 1, it is noted that an ink supply can
be supplied through a throughway for channel 38 which can be
constructed by means of deep anisotropic silicon trench etching
such as that available from STS Limited ("Advanced Silicon Etching
Using High Density Plasmas" by J. K. Bhardwaj, H. Ashraf, page 224
of Volume 2639 of the SPIE Proceedings in Micro Machining and Micro
Fabrication Process Technology). The ink supply flows from channel
38 through spaced apart apertures 40 (see also FIG. 7) into chamber
12. The apertures 40 are defined between poles 241, forming a
filter 341 (see FIG. 7). Importantly, the poles 241 which can
comprise silicon nitride or similar insulating material act to
remove foreign bodies from the ink flow. The poles 241 also help to
pinch the PTFE actuator 13 to a base CMOS layer 18, the pinching
providing an important assistance for the thermal actuator 13 so as
to ensure a substantially decreased likelihood of the thermal
actuator layer 13 separating from a base CMOS layer 18.
A series of sacrificial etchant holes 19 are defined in a top wall
48 of the chamber 12 to allow sacrificial etchant to enter the
chamber 12 during fabrication so as to increase the rate of
etching. The small size of the holes 19, does not affect the
operation of the device 10 substantially as the surface tension
across the holes 19 inhibit ink from being ejected from these
holes, whereas the larger sized port 11 allows for the ejection of
ink.
Turning now to FIG. 7, there is illustrated an exploded perspective
view of a single nozzle 10. The nozzles 10 can be formed in layers
starting with a silicon wafer substrate 41 having a CMOS layer 18
on top thereof as required. The CMOS layer 18 provides the various
drive circuitry for driving the actuator 13.
On top of the CMOS layer 18 a nitride layer 42 is deposited,
providing primarily protection for lower layers from corrosion or
etching. Next a PTFE layer 26 is constructed having the
aforementioned holes 25 (see FIG. 1), and posts 27 (see FIG. 1).
The structure of the PTFE layer 26 can be formed by first laying
down a sacrificial glass layer (not shown) onto which the PTFE
layer 26 is deposited. The PTFE layer 26 includes various features,
for example, a lower ridge portion 30 in addition to vias for
subsequent material layers.
In construction of the actuator 13 (FIG. 1), the process of
creating a first PTFE layer 60 proceeds by laying down a
sacrificial layer on top of the layer 26 in which the air bubble
17, underneath the actuator 13 (FIG. 1), subsequently forms. On top
of this is formed a first PTFE layer utilizing the relevant mask.
Preferably, the PTFE layer includes vias for the subsequent copper
interconnections. Next, a copper layer 43 is deposited on top of
the first PTFE layer 60 and a subsequent PTFE layer 61 is deposited
on top of the copper layer 43, in each case utilizing the required
mask.
The nitride layer 46 can be formed by the utilization of a
sacrificial glass layer which is masked and etched as required to
form side walls and the filter 341. Subsequently, the top nitride
layer 48 is deposited again utilizing the appropriate mask having
considerable holes 19 as required. Subsequently, the various
sacrificial layers can be etched away so as to release the
structure of the thermal actuator.
In FIG. 8 there is illustrated a section of an ink jet printhead
configuration 90 utilizing ink jet nozzles constructed in
accordance with the preferred embodiment 91. The configuration 90
can be utilized in a three color process, 16 Oodpi printhead
utilizing three sets of two rows of nozzle chambers 92,93, which
are interconnected to one ink supply channel 94, for each set. The
three supply channels 94, 95, 96 are interconnected to cyan
colored, magenta colored and yellow colored ink reservoirs
respectively. Ink is supplied through respective apertures 200,
202, 204 formed in the wafer substrate and extending through the
wafer substrate 206 to the back surface thereof.
It would be appreciated by a person skilled in the art that
numerous variations and/or modifications may be made to the present
invention as shown in the specific embodiment without departing
from the spirit or scope of the invention as broadly described. The
present embodiment is, therefore, to be considered in all respects
to be illustrative and not restrictive.
Ink Jet Technologies
The embodiments of the invention use an ink jet printer type
device. Of course many different devices could be used. However
presently popular ink jet printing technologies are unlikely to be
suitable.
The most significant problem with thermal inkjet is power
consumption. This is approximately 100 times that required for high
speed, and stems from the energy-inefficient means of drop
ejection. This involves the rapid boiling of water to produce a
vapor bubble which expels the ink. Water has a very high heat
capacity, and must be superheated in thermal inkjet applications.
This leads to an efficiency of around 0.02%, from electricity input
to drop momentum (and increased surface area) out.
The most significant problem with piezoelectric inkjet is size and
cost. Piezoelectric crystals have a very small deflection at
reasonable drive voltages, and therefore require a large area for
each nozzle. Also, each piezoelectric actuator must be connected to
its drive circuit on a separate substrate. This is not a
significant problem at the current limit of around 300 nozzles per
print head, but is a major impediment to the fabrication of
pagewidth print heads with 19,200 nozzles.
Ideally, the inkjet technologies used meet the stringent
requirements of in-camera digital color printing and other high
quality, high speed, low cost printing applications. To meet the
requirements of digital photography, new inkjet technologies have
been created. The target features include:
low power (less than 10 Watts)
high resolution capability (1,600 dpi or more)
photographic quality output
low manufacturing cost
small size (pagewidth times minimum cross section)
high speed (<2 seconds per page).
All of these features can be met or exceeded by the inkjet systems
described below with differing levels of difficulty. Forty-five
different inkjet technologies have been developed by the Assignee
to give a wide range of choices for high volume manufacture. These
technologies form part of separate applications assigned to the
present Assignee as set out in the table below.
The inkjet designs shown here are suitable for a wide range of
digital printing systems, from battery powered one-time use digital
cameras, through to desktop and network printers, and through to
commercial printing systems
For ease of manufacture using standard process equipment, the print
head is designed to be a monolithic 0.5 micron CMOS chip with MEMS
post processing. For color photographic applications, the print
head is 100 mm long, with a width which depends upon the inkjet
type. The smallest print head designed is IJ38, which is 0.35 mm
wide, giving a chip area of 35 square mm. The print heads each
contain 19,200 nozzles plus data and control circuitry.
Ink is supplied to the back of the print head by injection molded
plastic ink channels. The molding requires 50 micron features,
which can be created using a lithographically micromachined insert
in a standard injection molding tool. Ink flows through holes
etched through the wafer to the nozzle chambers fabricated on the
front surface of the wafer. The print head is connected to the
camera circuitry by tape automated bonding.
Tables of Drop-on-Demand Ink Jets
Eleven important characteristics of the fundamental operation of
individual ink jet nozzles have been identified. These
characteristics are largely orthogonal, and so can be elucidated as
an eleven dimensional matrix. Most of the eleven axes of this
matrix include entries developed by the present assignee.
The following tables form the axes of an eleven dimensional table
of ink jet types.
Actuator mechanism (18 types)
Basic operation mode (7 types)
Auxiliary mechanism (8 types)
Actuator amplification or modification method (17 types)
Actuator motion (19 types)
Nozzle refill method (4 types)
Method of restricting back-flow through inlet (10 types)
Nozzle clearing method (9 types)
Nozzle plate construction (9 types)
Drop ejection direction (5 types)
Ink type (7 types)
The complete eleven dimensional table represented by these axes
contains 36.9 billion possible configurations of ink jet nozzle.
While not all of the possible combinations result in a viable ink
jet technology, many million configurations are viable. It is
clearly impractical to elucidate all of the possible
configurations. Instead, certain ink jet types have been
investigated in detail. These are designated IJ01 to IJ45 which
matches the docket numbers in the in the table under the heading
Cross References to Related Applications.
Other ink jet configurations can readily be derived from these
forty-five examples by substituting alternative configurations
along one or more of the 11 axes. Most of the IJ01 to IJ45 examples
can be made into ink jet print heads with characteristics superior
to any currently available ink jet technology.
Where there are prior art examples known to the inventor, one or
more of these examples are listed in the examples column of the
tables below. The IJ01 to IJ45 series are also listed in the
examples column. In some cases, a printer may be listed more than
once in a table, where it shares characteristics with more than one
entry.
Suitable applications for the ink jet technologies include: Home
printers, Office network printers, Short run digital printers,
Commercial print systems, Fabric printers, Pocket printers,
Internet WWW printers, Video printers, Medical imaging, Wide format
printers, Notebook PC printers, Fax machines, Industrial printing
systems, Photocopiers, Photographic minilabs etc.
The information associated with the aforementioned 11 dimensional
matrix are set out in the following tables.
ACTUATOR MECHANISM (APPLIED ONLY TO SELECTED INK DROPS) Description
Advantages Disadvantages Examples Thermal An electrothermal Large
force High power Canon Bubblejet bubble heater heats the ink to
generated Ink carrier limited to 1979 Endo et al GB above boiling
point, Simple construction water patent 2,007,162 transferring
significant No moving parts Low efficiency Xerox heater-in-pit heat
to the aqueous Fast operation High temperatures 1990 Hawkins et al
ink. A bubble Small chip area required U.S. Pat. No. 4,899,181
nucleates and quickly required for actuator High mechanical
Hewlett-Packard TIJ forms, expelling the stress 1982 Vaught et al
ink. Unusual materials U.S. Pat. No. 4,490,728 The efficiency of
the required process is low, with Large drive typically less than
transistors 0.05% of the electrical Cavitation causes energy being
actuator failure transformed into Kogation reduces kinetic energy
of the bubble formation drop. Large print heads are difficult to
fabricate Piezo- A piezoelectric crystal Low power Very large area
Kyser et al U.S. Pat. No. electric such as lead consumption
required for actuator 3,946,398 lanthanum zirconate Many ink types
can Difficult to integrate Zoltan U.S. Pat. No. (PZT) is
electrically be used with electronics 3,683,212 activated, and
either Fast operation High voltage drive 1973 Stemme U.S. Pat. No.
expands, shears, or High efficiency transistors required 3,747,120
bends to apply Full pagewidth print Epson Stylus pressure to the
ink, heads impractical Tektronix ejecting drops. due to actuator
size IJ04 Requires electrical poling in high field strengths during
manufacture Electro- An electric field is Low power Low maximum
Seiko Epson, Usui strictive used to activate consumption strain
(approx. et all JP 253401/96 electrostriction in Many ink types can
0.01%) IJ04 relaxor materials such be used Large area required as
lead lanthanum Low thermal for actuator due to zirconate titanate
expansion low strain (PLZT) or lead Electric field Response speed
is magnesium niobate strength required marginal (.about.10 .mu.s)
(PMN). (approx. 3.5 V/.mu.m) High voltage drive can be generated
transistors required without difficulty Full pagewidth print Does
not require heads impractical electrical poling due to actuator
size Ferro- An electric field is Low power Difficult to integrate
IJ04 electric used to induce a phase consumption with electronics
transition between the Many ink types can Unusual materials
antiferroelectric (AFE) be used such as PLZSnT are and
ferroelectric (FE) Fast operation required phase. Perovskite (<1
.mu.s) Actuators require a materials such as tin Relatively high
large area modified lead longitudinal strain lanthanum zirconate
High efficiency titanate (PLZSnT) Electric field exhibit large
strains of strength of around 3 up to 1% associated V/.mu.m can be
readily with the AFE to FE provided phase transition. Electro-
Conductive plates are Low power Difficult to operate IJ02, IJ04
static separated by a consumption electrostatic devices plates
compressible or fluid Many ink types can in an aqueous dielectric
(usually air). be used environment Upon application of a Fast
operation The electrostatic voltage, the plates actuator will
attract each other and normally need to be displace ink, causing
separated from the drop ejection. The ink conductive plates may
Very large area be in a comb or required to achieve honeycomb
structure, high forces or stacked to increase High voltage drive
the surface area and transistors may be therefore the force.
required Full pagewidth print heads are not competitive due to
actuator size Electro- A strong electric field Low current High
voltage 1989 Saito et al, static pull is applied to the ink,
consumption required U.S. Pat. No. 4,799,068 on ink whereupon Low
temperature May be damaged by 1989 Miura et al, electrostatic
attraction sparks due to air U.S. Pat. No. 4,810,954 accelerates
the ink breakdown Tone-jet towards the print Required field medium.
strength increases as the drop size decreases High voltage drive
transistors required Electrostatic field attracts dust Permanent An
electromagnet Low power Complex fabrication IJ07, IJ10 magnet
directly attracts a consumption Permanent magnetic electro-
permanent magnet, Many ink types can material such as magnetic
displacing ink and be used Neodymium Iron causing drop ejection.
Fast operation Boron (NdFeB) Rare earth magnets High efficiency
required. with a field strength Easy extension from High local
currents around 1 Tesla can be single nozzles to required used.
Examples are: pagewidth print Copper metalization Samarium Cobalt
heads should be used for (SaCo) and magnetic long materials in the
electromigration neodymium iron boron lifetime and low family
(NdFeB, resistivity NdDyFeBNb, Pigmented inks are NdDyFeB, etc)
usually infeasible Operating temperature limited to the Curie
temperature (around 540 K) Soft A solenoid induced a Low power
Complex fabrication IJ01, IJ05, IJ08, magnetic magnetic field in a
soft consumption Materials not IJ10, IJ12, IJ14, core magnetic core
or yoke Many ink types can usually present in a IJ15, IJ17 electro-
fabricated from a be used CMOS fab such as magnetic ferrous
material such Fast operation NiFe, CoNiFe, or as electroplated iron
High efficiency CoFe are required alloys such as CoNiFe Easy
extension from High local currents [1], CoFe, or NiFe single
nozzles to required alloys. Typically, the pagewidth print Copper
metalization soft magnetic material heads should be used for is in
two parts, which long are normally held electromigration apart by a
spring. lifetime and low When the solenoid is resistivity actuated,
the two parts Electroplating is attract, displacing the required
ink. High saturation flux density is required (2.0-2.1 T is
achievable with CoNiFe [1]) Lorenz The Lorenz force Low power Force
acts as a IJ06, IJ11, IJ13, force acting on a current consumption
twisting motion IJ16 carrying wire in a Many ink types can
Typically, only a magnetic field is be used quarter of the
utilized. Fast operation solenoid length This allows the High
efficiency provides force in a magnetic field to be Easy extension
from useful direction supplied externally to single nozzles to High
local currents the print head, for pagewidth print required example
with rare heads Copper metalization earth permanent should be used
for magnets. long Only the current electromigration carrying wire
need be lifetime and low fabricated on the print- resistivity head,
simplifying Pigmented inks are materials usually infeasible
requirements. Magneto- The actuator uses the Many ink types can
Force acts as a Fischenbeck, U.S. Pat. No. striction giant
magnetostrictive be used twisting motion 4,032,929 effect of
materials Fast operation Unusual materials IJ25 such as Terfenol-D
(an Easy extension from such as Terfenol-D alloy of terbium, single
nozzles to are required dysprosium and iron pagewidth print High
local currents developed at the Naval heads required Ordnance
Laboratory, High force is Copper metalization hence Ter-Fe-NOL).
available should be used for For best efficiency, the long actuator
should be pre- electromigration stressed to approx. 8 lifetime and
low MPa. resistivity Pre-stressing may be required Surface Ink
under positive Low power Requires Silverbrook, EP tension pressure
is held in a consumption supplementary force 0771 658 A2 and
reduction nozzle by surface Simple construction to effect drop
related patent tension. The surface No unusual separation
applications tension of the ink is materials required in Requires
special ink reduced below the fabrication surfactants bubble
threshold, High efficiency Speed may be causing the ink to Easy
extension from limited by surfactant egress from the single nozzles
to properties nozzle. pagewidth print heads Viscosity The ink
viscosity is Simple construction Requires Silverbrook, EP reduction
locally reduced to No unusual supplementary force 0771 658 A2 and
select which drops are materials required in to effect drop related
patent to be ejected. A fabrication separation applications
viscosity reduction can Easy extension from Requires special ink be
achieved single nozzles to viscosity properties electrothermally
with pagewidth print High speed is most inks, but special heads
difficult to achieve inks can be engineered Requires oscillating
for a 100:1 viscosity ink pressure reduction. A high temperature
difference (typically 80 degrees) is required Acoustic An acoustic
wave is Can operate without Complex drive 1993 Hadimioglu et
generated and a nozzle plate circuitry al, EUP 550,192 focussed
upon the Complex fabrication 1993 Elrod et al, drop ejection
region. Low efficiency EUP 572,220 Poor control of drop position
Poor control of drop volume Thermo- An actuator which Low power
Efficient aqueous IJ03, IJ09, IJ17,
elastic relies upon differential consumption operation requires a
IJ18, IJ19, IJ20, bend thermal expansion Many ink types can thermal
insulator on IJ21, IJ22, IJ23, actuator upon Joule heating is be
used the hot side IJ24, IJ27, IJ28, used. Simple planar Corrosion
IJ29, IJ30, IJ31, fabrication prevention can be IJ32, IJ33, IJ34,
Small chip area difficult IJ35, IJ36, IJ37, required for each
Pigmented inks may IJ38, IJ39, IJ40, actuator be infeasible, as
IJ41 Fast operation pigment particles High efficiency may jam the
bend CMOS compatible actuator voltages and currents Standard MEMS
processes can be used Easy extension from single nozzles to
pagewidth print heads High CTE A material with a very High force
can be Requires special IJ09, IJ17, IJ18, thermo- high coefficient
of generated material (e.g. PTFE) IJ20, IJ21, IJ22, elastic thermal
expansion Three methods of Requires a PTFE IJ23, IJ24, IJ27,
actuator (CTE) such as PTFE deposition are deposition process,
IJ28, IJ29, IJ30, polytetrafluoroethylene under development: which
is not yet IJ31, IJ42, IJ43, (PTFE) is used. As chemical vapor
standard in ULSI IJ44 high CTE materials deposition (CVD), fabs are
usually non- spin coating, and PTFE deposition conductive, a heater
evaporation cannot be followed fabricated from a PTFE is a
candidate with high conductive material is for low dielectric
temperature (above incorporated. A 50 .mu.m constant insulation
350.degree. C.) processing long PTFE bend in ULSI Pigmented inks
may actuator with Very low power be infeasible, as polysilicon
heater and consumption pigment particles 15 mW power input Many ink
types can may jam the bend can provide 180 .mu.N be used actuator
force and 10 .mu.m Simple planar deflection. Actuator fabrication
motions include: Small chip area Bend required for each Push
actuator Buckle Fast operation Rotate High efficiency CMOS
compatible voltages and currents Easy extension from single nozzles
to pagewidth print heads Conduct- A polymer with a high High force
can be Requires special IJ24 ive coefficient of thermal generated
materials polymer expansion (such as Very low power development
(High thermo- PTFE) is doped with consumption CTE conductive
elastic conducting substances Many ink types can polymer) actuator
to increase its be used Requires a PTFE conductivity to about 3
Simple planar deposition process, orders of magnitude fabrication
which is not yet below that of copper. Small chip area standard in
ULSI The conducting required for each fabs polymer expands actuator
PTFE deposition when resistively Fast operation cannot be followed
heated. High efficiency with high Examples of CMOS compatible
temperature (above conducting dopants voltages and 350.degree. C.)
processing include: currents Evaporation and Carbon nanotubes Easy
extension from CVD deposition Metal fibers single nozzles to
techniques cannot Conductive polymers pagewidth print be used such
as doped heads Pigmented inks may polythiophene be infeasible, as
Carbon granules pigment particles may jam the bend actuator Shape A
shape memory alloy High force is Fatigue limits IJ26 memory such as
TiNi (also available (stresses maximum number alloy known as
Nitinol - of hundreds of MPa) of cycles Nickel Titanium alloy Large
strain is Low strain (1%) is developed at the Naval available (more
than required to extend Ordnance Laboratory) 3%) fatigue resistance
is thermally switched High corrosion Cycle rate limited between its
weak resistance by heat removal martensitic state and Simple
construction Requires unusual its high stiffness Easy extension
from materials (TiNi) austenic state. The single nozzles to The
latent heat of shape of the actuator pagewidth print transformation
must in its martensitic state heads be provided is deformed
relative to Low voltage High current the austenic shape. operation
operation The shape change Requires pre- causes ejection of a
stressing to distort drop. the martensitic state Linear Linear
magnetic Linear Magnetic Requires unusual IJ12 Magnetic actuators
include the actuators can be semiconductor Actuator Linear
Induction constructed with materials such as Actuator (LIA), Linear
high thrust, long soft magnetic alloys Permanent Magnet travel, and
high (e.g. CoNiFe) Synchronous Actuator efficiency using Some
varieties also (LPMSA), Linear planar require permanent Reluctance
semiconductor magnetic materials Synchronous Actuator fabrication
such as Neodymium (LRSA), Linear techniques iron boron (NdFeB)
Switched Reluctance Long actuator travel Requires complex Actuator
(LSRA), and is available multi-phase drive the Linear Stepper
Medium force is circuitry Actuator (LSA). available High current
Low voltage operation operation
BASIC OPERATION MODE Description Advantages Disadvantages Examples
Actuator This is the simplest Simple operation Drop repetition rate
Thermal ink jet directly mode of operation: the No external fields
is usually limited to Piezoelectric ink jet pushes ink actuator
directly required around 10 kHz. IJ01, IJ02, IJ03, supplies
sufficient Satellite drops can However, this is not IJ04, IJ05,
IJ06, kinetic energy to expel be avoided if drop fundamental to the
IJ07, IJ09, IJ11, the drop. The drop velocity is less than method,
but is IJ12, IJ14, IJ16, must have a sufficient 4 m/s related to
the refill IJ20, IJ22, IJ23, velocity to overcome Can be efficient,
method normally IJ24, IJ25, IJ26, the surface tension. depending
upon the used IJ27, IJ28, IJ29, actuator used All of the drop IJ30,
IJ31, IJ32, kinetic energy must IJ33, IJ34, IJ35, be provided by
the IJ36, IJ37, IJ38, actuator IJ39, IJ40, IJ41, Satellite drops
IJ42, IJ43, IJ44 usually form if drop velocity is greater than 4.5
m/s Proximity The drops to be Very simple print Requires close
Silverbrook, EP printed are selected by head fabrication can
proximity between 0771 658 A2 and some manner (e.g. be used the
print head and related patent thermally induced The drop selection
the print media or applications surface tension means does not need
transfer roller reduction of to provide the May require two
pressurized ink). energy required to print heads printing Selected
drops are separate the drop alternate rows of the separated from
the ink from the nozzle image in the nozzle by Monolithic color
contact with the print print heads are medium or a transfer
difficult roller. Electro- The drops to be Very simple print
Requires very high Silverbrook, EP static pull printed are selected
by head fabrication can electrostatic field 0771 658 A2 and on ink
some manner (e.g. be used Electrostatic field related patent
thermally induced The drop selection for small nozzle applications
surface tension means does not need sizes is above air Tone-Jet
reduction of to provide the breakdown pressurized ink). energy
required to Electrostatic field Selected drops are separate the
drop may attract dust separated from the ink from the nozzle in the
nozzle by a strong electric field. Magnetic The drops to be Very
simple print Requires magnetic Silverbrook, EP pull on ink printed
are selected by head fabrication can ink 0771 658 A2 and some
manner (e.g. be used Ink colors other than related patent thermally
induced The drop selection black are difficult applications surface
tension means does not need Requires very high reduction of to
provide the magnetic fields pressurized ink). energy required to
Selected drops are separate the drop separated from the ink from
the nozzle in the nozzle by a strong magnetic field acting on the
magnetic ink. Shutter The actuator moves a High speed (>50
Moving parts are IJ13, IJ17, IJ21 shutter to block ink kHz)
operation can required flow to the nozzle. The be achieved due to
Requires ink ink pressure is pulsed reduced refill time pressure
modulator at a multiple of the Drop timing can be Friction and wear
drop ejection very accurate must be considered frequency. The
actuator energy Stiction is possible can be very low Shuttered The
actuator moves a Actuators with Moving parts are IJ08, IJ15, IJ18,
grill shutter to block ink small travel can be required IJ19 flow
through a grill to used Requires ink the nozzle. The shutter
Actuators with pressure modulator movement need only small force
can be Friction and wear be equal to the width used must be
considered of the grill holes. High speed (>50 Stiction is
possible kHz) operation can be achieved Pulsed A pulsed magnetic
Extremely low Requires an external IJ10 magnetic field attracts an
`ink energy operation is pulsed magnetic pull on ink pusher` at the
drop possible field pusher ejection frequency. An No heat
dissipation Requires special actuator controls a problems materials
for both catch, which prevents the actuator and the the ink pusher
from ink pusher moving when a drop is Complex not to be ejected.
construction
AUXILIARY MECHANISM (APPLIED TO ALL NOZZLES) Description Advantages
Disadvantages Examples None The actuator directly Simplicity of
Drop ejection Most ink jets, fires the ink drop, and construction
energy must be including there is no external Simplicity of
supplied by piezoelectric and field or other operation individual
nozzle thermal bubble. mechanism required. Small physical size
actuator IJ01, IJ02, IJ03, IJ04, IJ05, IJ07, IJ09, IJ11, IJ12,
IJ14, IJ20, IJ22, IJ23, IJ24, IJ25, IJ26, IJ27, IJ28, IJ29, IJ30,
IJ31, IJ32, IJ33, IJ34, IJ35, IJ36, IJ37, IJ38, IJ39, IJ40, IJ41,
IJ42, IJ43, IJ44 Oscillating The ink pressure Oscillating ink
Requires external Silverbrook, EP ink oscillates, providing
pressure can provide ink pressure 0771 658 A2 and pressure much of
the drop a refill pulse, oscillator related patent (including
ejection energy. The allowing higher Ink pressure phase
applications acoustic actuator selects which operating speed and
amplitude must IJ08, IJ13, IJ15, stimul- drops are to be fired The
actuators may be carefully IJ17, IJ18, IJ19, ation) by selectively
operate with much controlled IJ21 blocking or enabling lower energy
Acoustic reflections nozzles. The ink Acouitic lenses can in the
ink chamber pressure oscillation be used to focus the must be
designed may be achieved by sound on the for vibrating the print
nozzles head, or preferably by an actuator in the ink supply. Media
The print head is Low power Precision assembly Silverbrook, EP
proximity placed in close High accuracy required 0771 658 A2 and
proximity to the print Simple print head Paper fibers may related
patent medium. Selected construction cause problems applications
drops protrude from Cannot print on the print head further rough
substrates than unselected drops, and contact the print medium. The
drop soaks into the medium fast enough to cause drop separation.
Transfer Drops are printed to a High accuracy Bulky Silverbrook, EP
roller transfer roller instead Wide range of print Expensive 0771
658 A2 and of straight to the print substrates can be Complex
related patent medium. A transfer used construction applications
roller can also be used Ink can be dried on Tektronix hot melt for
proximity drop the transfer roller piezoelectric ink jet
separation. Any of the IJ series Electro- An electric field is Low
power Field strength Silverbrook, EP static used to accelerate
Simple print head required for 0771 658 A2 and selected drops
towards Construction separation of small related patent the print
medium. drops is near or applications above air Tone-Jet breakdown
Direct A magnetic field is Low power Requires magnetic Silverbrook,
EP magnetic used to accelerate Simple print head ink 0771 658 A2
and field selected drops of construction Requires strong related
patent magnetic ink towards magnetic field applications the print
medium. Cross The print head is Does not require Requires external
IJ06, IJ16 magnetic placed in a constant magnetic materials magnet
field magnetic field. The to be integrated in Current densities
Lorenz force in a the print head may be high, current carrying wire
manufacturing resulting in is used to move the process
electromigration actuator. problems Pulsed A pulsed magnetic Very
low power Complex print head IJ10 magnetic field is used to
operation is possible construction field cyclically attract a Small
print head Magnetic materials paddle, which pushes size required in
print on the ink. A small head actuator moves a catch, which
selectively prevents the paddle from moving.
ACTUATOR AMPLIFICATION OR MODIFICATION METHOD Description
Advantages Disadvantages Examples None No actuator Operational Many
actuator Thermal Bubble Ink mechanical simplicity mechanisms have
jet amplification is used. insufficient travel, IJ01, IJ02, IJ06,
The actuator directly or insufficient force, IJ07, IJ16, IJ25,
drives the drop to efficiently drive IJ26 ejection process. the
drop ejection process Differential An actuator material Provides
greater High stresses are Piezoelectric expansion expands more on
one travel in a reduced involved IJ03, IJ09, IJ17, bend side than
on the other. print head area Care must be taken IJ18, IJ19, IJ20,
actuator The expansion may be that the materials do IJ21, IJ22,
IJ23, thermal, piezoelectric, not delaminate IJ24, IJ27, IJ29,
magnetostrictive, or Residual bend IJ30, IJ31, IJ32, other
mechanism. The resulting from high IJ33, IJ34, IJ35, bend actuator
converts temperature or high IJ36, IJ37, IJ38, a high force low
travel stress during IJ39, IJ42, IJ43, actuator mechanism to
formation IJ44 high travel, lower force mechanism. Transient A
trilayer bend Very good High stresses are IJ40, IJ41 bend actuator
where the two temperature stability involved actuator outside
layers are High speed, as a Care must be taken identical. This
cancels new drop can be that the materials do bend due to ambient
fired before heat not delaminate temperature and dissipates
residual stress. The Cancels residual actuator only responds stress
of formation to transient heating of one side or the other. Reverse
The actuator loads a Better coupling to Fabrication IJ05, IJ11
spring spring. When the the ink complexity actuator is turned off,
High stress in the the spring releases. spring This can reverse the
force/distance curve of the actuator to make it compatible with the
force/time requirements of the drop ejection. Actuator A series of
thin Increased travel Increased Some piezoelectric stack actuators
are stacked. Reduced drive fabrication ink jets This can be voltage
complexity IJ04 appropriate where Increased possibility actuators
require high of short circuits due electric field strength, to
pinholes such as electrostatic and piezoelectric actuators.
Multiple Multiple smaller Increases the force Actuator forces may
IJ12, IJ13, IJ18, actuators actuators are used available from an
not add linearly, IJ20, IJ22, IJ28, simultaneously to actuator
reducing efficiency IJ42, IJ43 move the ink. Each Multiple
actuators actuator need provide can be positioned to only a portion
of the control ink flow force required. accurately Linear A linear
spring is used Matches low travel Requires print head IJ15 Spring
to transform a motion actuator with higher area for the spring with
small travel and travel requirements high force into a Non-contact
method longer travel, lower of motion force motion. transformation
Coiled A bend actuator is Increases travel Generally restricted
IJ17, IJ21, IJ34, actuator coiled to provide Reduces chip area to
planar IJ35 greater travel in a Planar implementations reduced chip
area. implementations are due to extreme relatively easy to
fabrication difficulty fabricate. in other orientations. Flexure A
bend actuator has a Simple means of Care must be taken IJ10, IJ19,
IJ33 bend small region near the increasing travel of not to exceed
the actuator fixture point, which a bend actuator elastic limit in
the flexes much more flexure area readily than the Stress
distribution is remainder of the very uneven actuator. The actuator
Difficult to flexing is effectively accurately model converted from
an with finite element even coiling to an analysis angular bend,
resulting in greater travel of the actuator tip. Catch The actuator
controls a Very low actuator Complex IJ10 small catch. The catch
energy construction either enables or Very small actuator Requires
external disables movement of size force an ink pusher that is
Unsuitable for controlled in a bulk pigmented inks manner. Gears
Gears can be used to Low force, low Moving parts are IJ13 increase
travel at the travel actuators can required expense of duration. be
used Several actuator Circular gears, rack Can be fabricated cycles
are required and pinion, ratchets, using standard More complex
drive and other gearing surface MEMS electronics methods can be
used. processes Complex construction Friction, friction, and wear
are possible Buckle A buckle plate can be Very fast movement Must
stay within S. Hirata et al, "An plate used to change a slow
achievable elastic limits of the Ink-jet Head Using actuator into a
fast materials for long Diaphragm motion. It can also device life
Microactuator", convert a high force, High stresses Proc. IEEE
MEMS, low travel actuator involved Feb. 1996, pp 418- into a high
travel, Generally high 423. medium force motion. power requirement
IJ18, IJ27 Tapered A tapered magnetic Linearizes the Complex IJ14
magnetic pole can increase magnetic construction pole travel at the
expense force/distance curve of force. Lever A lever and fulcrum is
Matches low travel High stress around IJ32, IJ36, IJ37 used to
transform a actuator with higher the fulcrum motion with small
travel requirements travel and high force Fulcrum area has no into
a motion with linear movement, longer travel and and can be used
for lower force. The lever a fluid seal can also reverse the
direction of travel. Rotary The actuator is High mechanical Complex
IJ28 impeller connected to a rotary advantage construction
impeller. A small The ratio of force to Unsuitable for angular
deflection of travel of the actuator pigmented inks the actuator
results in can be matched to a rotation of the the nozzle impeller
vanes, which requirements by push the ink against varying the
number stationary vanes and of impeller vanes out of the nozzle.
Acoustic A refractive or No moving parts Large area required 1993
Hadimioglu et lens diffractive (e.g. zone Only relevant for al, EUP
550,192 plate) acoustic lens is acoustic ink jets 1993 Elrod et al,
used to concentrate EUP 572,220 sound waves. Sharp A sharp point is
used Simple construction Difficult to fabricate Tone-jet conductive
to concentrate an using standard VLSI point electrostatic field.
processes for a surface ejecting ink- jet Only relevant for
electrostatic ink jets
ACTUATOR MOTION Description Advantages Disadvantages Examples
Volume The volume of the Simple construction High energy is
Hewlett-Packard expansion actuator changes, in the case of
typically required to Thermal Ink jet pushing the ink in all
thermal ink jet achieve volume Canon Bubblejet directions.
expansion. This leads to thermal stress, cavitation, and kogation
in thermal ink jet implementations Linear, The actuator moves in
Efficient coupling to High fabrication IJ01, IJ02, IJ04, normal to
a direction normal to ink drops ejected complexity may be IJ07,
IJ11, IJ14 chip the print head surface. normal to the required to
achieve surface The nozzle is typically surface perpendicular in
the line of motion movement. Parallel to The actuator moves
Suitable for planar Fabrication IJ12, IJ13, IJ15, chip parallel to
the print fabrication complexity IJ33, , IJ34, IJ35, surface head
surface. Drop Friction IJ36 ejection may still be Stiction normal
to the surface. Membrane An actuator with a The effective area of
Fabrication 1982 Howkins U.S. Pat. No. push high force but small
the actuator complexity 4,459,601 area is used to push a becomes
the Actuator size stiff membrane that is membrane area Difficulty
of in contact with the ink. integration in a VLSI process Rotary
The actuator causes Rotary levers may Device complexity IJ05, IJ08,
IJ13, the rotation of some be used to increase May have friction at
IJ28 element, such a grill or travel a pivot point impeller Small
chip area requirements Bend The actuator bends A very small change
Requires the 1970 Kyser et al when energized. This in dimensions
can actuator to be made U.S. Pat. No. 3,946,398 may be due to be
converted to a from at least two 1973 Stemme U.S. Pat. No.
differential thermal large motion. distinct layers, or to 3,747,120
expansion, have a thermal IJ03, IJ09, IJ10, piezoelectric
difference across the IJ19, IJ23, IJ24, expansion, actuator IJ25,
IJ29, IJ30, magnetostriction, or IJ31, IJ33, IJ34, other form of
relative IJ35 dimensional change. Swivel The actuator swivels
Allows operation Inefficient coupling IJ06 around a central pivot.
where the net linear to the ink motion This motion is suitable
force on the paddle where there are is zero opposite forces Small
chip area applied to opposite requirements sides of the paddle,
e.g. Lorenz force. Straighten The actuator is Can be used with
Requires careful IJ26, IJ32 normally bent, and shape memory balance
of stresses straightens when alloys where the to ensure that the
energized. austenic phase is quiescent bend is planar accurate
Double The actuator bends in One actuator can be Difficult to make
IJ36, IJ37, IJ38 bend one direction when used to power two the
drops ejected by one element is nozzles. both bend directions
energized, and bends Reduced chip size. identical. the other way
when Not sensitive to A small efficiency another element is ambient
temperature loss compared to energized. equivalent single bend
actuators. Shear Energizing the Can increase the Not readily 1985
Fishbeck U.S. Pat. No. actuator causes a shear effective travel of
applicable to other 4,584,590 motion in the actuator piezoelectric
actuator material. actuators mechanisms Radial The actuator
squeezes Relatively easy to High force required 1970 Zoltan U.S.
Pat. No. con- an ink reservoir, fabricate single Inefficient
3,683,212 striction forcing ink from a nozzles from glass Difficult
to integrate constricted nozzle. tubing as with VLSI macroscopic
processes structures Coil/ A coiled actuator Easy to fabricate as
Difficult to fabricate IJ17, IJ21, IJ34, uncoil uncoils or coils
more a planar VLSI for non-planar IJ35 tightly. The motion of
process devices the free end of the Small area required, Poor
out-of-plane actuator ejects the ink. therefore low cost stiffness
Bow The actuator bows (or Can increase the Maximum travel is IJ16,
IJ18, IJ27 buckles) in the middle speed of travel constrained when
energized. Mechanically rigid High force required Push-Pull Two
actuators control The structure is Not readily suitable IJ18 a
shutter. One actuator pinned at both ends, for ink jets which pulls
the shutter, and so has a high out-of- directly push the ink the
other pushes it. plane rigidity Curl A set of actuators curl Good
fluid flow to Design complexity IJ20, IJ42 inwards inwards to
reduce the the region behind volume of ink that the actuator they
enclose. increases efficiency Curl A set of actuators curl
Relatively simple Relatively large IJ43 outwards outwards,
pressurizing construction chip area ink in a chamber surrounding
the actuators, and expelling ink from a nozzle in the chamber. Iris
Multiple vanes enclose High efficiency High fabrication IJ22 a
volume of ink. These Small chip area complexity simultaneously
rotate, Not suitable for reducing the volume pigmented inks between
the vanes. Acoustic The actuator vibrates The actuator can be Large
area required 1993 Hadimioglu et vibration at a high frequency.
physically distant for efficient al, EUP 550,192 from the ink
operation at useful 1993 Elrod et al, frequencies EUP 572,220
Acoustic coupling and crosstalk Complex drive circuitry Poor
control of drop volume and position None In various ink jet No
moving parts Various other Silverbrook, EP designs the actuator
tradeoffs are 0771 658 A2 and does not move. required to related
patent eliminate moving applications parts Tone-jet
NOZZLE REFILL METHOD Description Advantages Disadvantages Examples
Surface This is the normal way Fabrication Low speed Thermal ink
jet tension that ink jets are simplicity Surface tension
Piezoelectric ink jet refilled. After the Operational force
relatively IJ01-IJ07, IJ10-IJ14, actuator is energized, simplicity
small compared to IJ16, IJ20, IJ22-IJ45 it typically returns
actuator force rapidly to its normal Long refill time position.
This rapid usually dominates return sucks in air the total
repetition through the nozzle rate opening. The ink surface tension
at the nozzle then exerts a small force restoring the meniscus to a
minimum area. This force refills the nozzle. Shuttered Ink to the
nozzle High speed Requires common IJ08, IJ13, IJ15, oscillating
chamber is provided at Low actuator ink pressure IJ17, IJ18, IJ19,
ink a pressure that energy, as the oscillator IJ21 pressure
oscillates at twice the actuator need only May not be suitable drop
ejection open or close the for pigmented inks frequency. When a
shutter, instead of drop is to be ejected, ejecting the ink drop
the shutter is opened for 3 half cycles: drop ejection, actuator
return, and refill. The shutter is then closed to prevent the
nozzle chamber emptying during the next negative pressure cycle.
Refill After the main High speed, as the Requires two IJ09 actuator
actuator has ejected a nozzle is actively independent drop a second
(refill) refilled actuators per nozzle actuator is energized. The
refill actuator pushes ink into the nozzle chamber. The refill
actuator returns slowly, to prevent its return from emptying the
chamber again. Positive The ink is held a slight High refill rate,
Surface spill must Silverbrook, EP ink positive pressure. therefore
a high be prevented 0771 658 A2 and pressure After the ink drop is
drop repetition rate Highly hydrophobic related patent ejected, the
nozzle is possible print head surfaces applications chamber fills
quickly are required Alternative for:, as surface tension and
IJ01-IJ07, IJ10-IJ14, ink pressure both IJ16, IJ20, IJ22-IJ45
operate to refill the nozzle.
METHOD OF RESTRICTING BACK-FLOW THROUGH INLET Description
Advantages Disadvantages Examples Long inlet The ink inlet channel
Design simplicity Restricts refill rate Thermal ink jet channel to
the nozzle chamber Operational May result in a Piezoelectric ink
jet is made long and simplicity relatively large chip IJ42, IJ43
relatively narrow, Reduces crosstalk area relying on viscous Only
partially drag to reduce inlet effective back-flow. Positive The
ink is under a Drop selection and Requires a method Silverbrook, EP
ink positive pressure, so separation forces (such as a nozzle 0771
658 A2 and pressure that in the quiescent can be reduced rim or
effective related patent state some of the ink Fast refill time
hydrophobizing, or applications drop already protrudes both) to
prevent Possible operation from the nozzle. flooding of the of the
following: This reduces the ejection surface of IJ01-IJ07, IJ09-
pressure in the nozzle the print head. IJ12, IJ14, IJ16, chamber
which is IJ20, IJ22, , IJ23- required to eject a IJ34, IJ36-IJ41,
certain volume of ink. IJ44 The reduction in chamber pressure
results in a reduction in ink pushed out through the inlet. Baffle
One or more baffles The refill rate is not Design complexity HP
Thermal Ink Jet are placed in the inlet as restricted as the May
increase Tektronix ink flow. When the long inlet method.
fabrication piezoelectric ink jet actuator is energized, Reduces
crosstalk complexity (e.g. the rapid ink Tektronix hot melt
movement creates Piezoelectric print eddies which restrict heads).
the flow through the inlet. The slower refill process is
unrestricted, and does not result in eddies. Flexible In this
method recently Significantly Not applicable to Canon flap
disclosed by Canon, reduces back-flow most ink jet restricts the
expanding actuator for edge-shooter configurations inlet (bubble)
pushes on a thermal ink jet Increased flexible flap that devices
fabrication restricts the inlet. complexity Inelastic deformation
of polymer flap results in creep over extended use Inlet filter A
filter is located Additional Restricts refill rate IJ04, IJ12,
IJ24, between the ink inlet advantage of ink May result in IJ27,
IJ29, IJ30 and the nozzle filtration complex chamber. The filter
Ink filter may be construction has a multitude of fabricated with
no small holes or slots, additional process restricting ink flow.
steps The filter also removes particles which may block the nozzle.
Small inlet The ink inlet channel Design simplicity Restricts
refill rate IJ02, IJ37, IJ44 compared to the nozzle chamber May
result in a to nozzle has a substantially relatively large chip
smaller cross section area than that of the nozzle, OnIy partially
resulting in easier ink effective egress out of the nozzle than out
of the inlet. Inlet A secondary actuator Increases speed of
Requires separate IJ09 shutter controls the position of the ink-jet
print refill actuator and a shutter, closing off head operation
drive circuit the ink inlet when the main actuator is energized.
The inlet is The method avoids the Back-flow problem Requires
careful IJ01, IJ03, IJ05, located problem of inlet back- is
eliminated design to minimize IJ06, IJ07, IJ10, behind the flow by
arranging the the negative IJ11, IJ14, IJ16, ink- ink-pushing
surface of pressure behind the IJ22, IJ23, IJ25, pushing the
actuator between paddle IJ28, IJ31, IJ32, surface the inlet and the
IJ33, IJ34, IJ35, nozzle. IJ36, IJ39, IJ40, IJ41 Part of the The
actuator and a Significant Small increase in IJ07, IJ20, IJ26,
actuator wall of the ink reductions in back- fabrication IJ38 moves
to chamber are arranged flow can be complexity shut off so that the
motion of achieved the inlet the actuator closes off Compact
designs the inlet. possible Nozzle In some configurations Ink
back-flow None related to ink Silverbrook, EP actuator of ink jet,
there is no problem is back-flow on 0771 658 A2 and does not
expansion or eliminated actuation related patent result in movement
of an applications ink back- actuator which may Valve-jet flow
cause ink back-flow Tone-jet through the inlet.
NOZZLE CLEARING METHOD Description Advantages Disadvantages
Examples Normal All of the nozzles are No added May not be Most ink
jet systems nozzle fired periodically, complexity on the sufficient
to IJ01, IJ02, IJ03, firing before the ink has a print head
displace dried ink IJ04, IJ05, IJ06, chance to dry. When IJ07,
IJ09, IJ10, not in use the nozzles IJ11, IJ12, IJ14, are sealed
(capped) IJ16, IJ20, IJ22, against air. IJ23, IJ24, IJ25, The
nozzle firing is IJ26, IJ27, IJ28, usually performed IJ29, IJ30,
IJ31, during a special IJ32, IJ33, IJ34, clearing cycle, after
IJ36, IJ37, IJ38, first moving the print IJ39, IJ40,, IJ41, head to
a cleaning IJ42, IJ43, IJ44,, station. IJ45 Extra In systems which
heat Can be highly Requires higher Silverbrook, EP power to the
ink, but do not boil effective if the drive voltage for 0771 658 A2
and ink heater it under normal heater is adjacent to clearing
related patent situations, nozzle the nozzle May require larger
applications clearing can be drive transistors achieved by over-
powering the heater and boiling ink at the nozzle. Rapid The
actuator is fired in Does not require Effectiveness May be used
with: success- rapid succession. In extra drive circuits depends
IJ0I, IJ02, IJ03, ion of some configurations, on the print head
substantially upon IJ04, IJ05, IJ06, actuator this may cause heat
Can be readily the configuration of IJ07, IJ09, IJ10, pulses
build-up at the nozzle controlled and the ink jet nozzle IJ11,
IJ14, IJ16, which boils the ink, initiated by digital IJ20, IJ22,
IJ23, clearing the nozzle. In logic IJ24, IJ25, IJ27, other
situations, it may IJ28, IJ29, IJ30, cause sufficient IJ31, IJ32,
IJ33, vibrations to dislodge IJ34, IJ36, IJ37, clogged nozzles.
IJ38, IJ39, IJ40, IJ41, IJ42, IJ43, IJ44, IJ45 Extra Where an
actuator is A simple solution Not suitable where May be used with:
power to not normally driven to where applicable there is a hard
limit IJ03, IJ09, IJ16, ink the limit of its motion, to actuator
IJ20, IJ23, IJ24, pushing nozzle clearing may be movement IJ25,
IJ27, IJ29, actuator assisted by providing IJ30, IJ31, IJ32, an
enhanced drive IJ39, IJ40, IJ41, signal to the actuator. IJ42,
IJ43, IJ44, IJ45 Acoustic An ultrasonic wave is A high nozzle High
IJ08, IJ13, IJ15, resonance applied to the ink clearing capability
implementation cost IJ17, IJ18, IJ19, chamber. This wave is can be
achieved if system does not IJ21 of an appropriate May be already
include an amplitude and implemented at very acoustic actuator
frequency to cause low cost in systems sufficient force at the
which already nozzle to clear include acoustic blockages. This is
actuators easiest to achieve if the ultrasonic wave is at a
resonant frequency of the ink cavity. Nozzle A microfabricated Can
clear severely Accurate Silverbrook, EP clearing plate is pushed
against clogged nozzles mechanical 0771 658 A2 and plate the
nozzles. The plate alignment is related patent has a post for every
required applications nozzle. A post moves Moving parts are through
each nozzle, required displacing dried ink. There is risk of damage
to the nozzles Accurate fabrication is required Ink The pressure of
the ink May be effective Requires pressure May be used with
pressure is temporarily where other pump or other all IJ series ink
jets pulse increased so that ink methods cannot be pressure
actuator streams from all of the used Expensive nozzles. This may
be Wasteful of ink used in conjunction with actuator energizing.
Print head A flexible `blade` is Effective for planar Difficult to
use if Many ink jet wiper wiped across the print print head
surfaces print head surface is systems head surface. The Low cost
non-planar or very blade is usually fragile fabricated from a
Requires flexible polymer, e.g. mechanical parts rubber or
synthetic Blade can wear out elastomer. in high volume print
systems Separate A separate heater is Can be effective Fabrication
Can be used with ink boiling provided at the nozzle where other
nozzle complexity many IJ series ink heater although the normal
clearing methods jets drop e-ection cannot be used mechanism does
not Can be implemented require it. The heaters at no additional
cost do not require in some ink jet individual drive configurations
circuits, as many nozzles can be cleared simultaneously, and no
imaging is required
NOZZLE PLATE CONSTRUCTION Description Advantages Disadvantages
Examples Electro- A nozzle plate is Fabrication High temperatures
Hewlett Packard formed separately fabricated simplicity and
pressures are Thermal Ink jet nickel from electroformed required to
bond nickel, and bonded to nozzle plate the print head chip.
Minimum thickness constraints Differential thermal expansion Laser
Individual nozzle No masks required Each hole must be Canon
Bubblejet ablated or holes are ablated by an Can be quite fast
individually formed 1988 Sercel et al., drilled intense UV laser in
a Some control over Special equipment SPIE, Vol. 998 polymer nozzle
plate, which is nozzle profile is required Excimer Beam typically a
polymer possible Slow where there Applications, pp. such as
polyimide or Equipment required are many thousands 76-83
polysulphone is relatively low cost of nozzles per print 1993
Watanabe et head al., U.S. Pat. No. 5,208,604 May produce thin
burrs at exit holes Silicon A separate nozzle High accuracy is Two
part K. Bean, IEEE micro- plate is attainable construction
Transactions on machined micromachined from High cost Electron
Devices, single crystal silicon, Requires precision Vol. ED-25, No.
10, and bonded to the alignment 1978, pp 1185-1195 print head
wafer. Nozzles may be Xerox 1990 clogged by adhesive Hawkins et
al., U.S. Pat. No. 4,899,181 Glass Fine glass capillaries No
expensive Very small nozzle 1970 Zoltan U.S. Pat. No. capillaries
are drawn from glass equipment required sizes are difficult to
3,683,212 tubing. This method Simple to make form has been used for
single nozzles Not suited for mass making individual production
nozzles, but is difficult to use for bulk manufacturing of print
heads with thousands of nozzles. Monolithic, The nozzle plate is
High accuracy (<1 Requires sacrificial Silverbrook, EP surface
deposited as a layer .mu.m) layer under the 0771 658 A2 and micro-
using standard VLSI Monolithic nozzle plate to form related patent
machined deposition techniques. Low cost the nozzle chamber
applications using VLSI Nozzles are etched in Existing processes
Surface may be IJ01, IJ02, IJ04, litho- the nozzle plate using can
be used fragile to the touch IJ11, IJ12, IJ17, graphic VLSI
lithography and IJ18, IJ20, IJ22, processes etching. IJ24, IJ27,
IJ28, IJ29, IJ30, IJ31, IJ32, IJ33, IJ34, IJ36, IJ37, IJ38, IJ39,
IJ40, IJ41, IJ42, IJ43, IJ44 Monolithic, The nozzle plate is a High
accuracy (<1 Requires long etch IJ03, IJ05, IJ06, etched buried
etch stop in the .mu.m) times IJ07, IJ08, IJ09, through wafer.
Nozzle Monolithic Requires a support IJ10, IJ13, IJ14, substrate
chambers are etched in Low cost wafer IJ15, IJ16, IJ19, the front
of the wafer, No differential IJ21, IJ23, IJ25, and the wafer is
expansion IJ26 thinned from the back side. Nozzles are then etched
in the etch stop layer. No nozzle Various methods have No nozzles
to Difficult to control Ricoh 1995 Sekiya et al plate been tried to
eliminate become clogged drop position U.S. Pat. No. 5,412,413 the
nozzles entirely, to accurately 1993 Hadimioglu et prevent nozzle
Crosstalk problems al EUP 550,192 clogging. These 1993 Elrod et al
include thermal bubble EUP 572,220 mechanisms and acoustic lens
mechanisms Trough Each drop ejector has Reduced Drop firing IJ35 a
trough through manufacturing direction is sensitive which a paddle
moves. complexity to wicking. There is no nozzle Monolithic plate.
Nozzle slit The elimination of No nozzles to Difficult to control
1989 Saito et al instead of nozzle holes and become clogged drop
position U.S. Pat. No. 4,799,068 individual replacement by a slit
accurately nozzles encompassing many Crosstalk problems actuator
positions reduces nozzle clogging, but increases crosstalk due to
ink surface waves
DROP EJECTION DIRECTION Description Advantages Disadvantages
Examples Edge Ink flow is along the Simple construction Nozzles
limited to Canon Bubblejet (`edge surface of the chip, No silicon
etching edge 1979 Endo et al GB shooter`) and ink drops are
required High resolution is patent 2,007,162 ejected from the chip
Good heat sinking difficult Xerox heater-in-pit edge. via substrate
Fast color printing 1990 Hawkins et al Mechanically strong requires
one print U.S. Pat. No. 4,899,181 Ease of chip head per color
Tone-jet handing Surface Ink flow is along the No bulk silicon
Maximum ink flow Hewlett-Packard TIJ (`roof surface of the chip,
etching required is severely restricted 1982 Vaught et al shooter`)
and ink drops are Silicon can make an U.S. Pat. No. 4,490,728
ejected from the chip effective heat sink IJ02, IJ11, IJ12,
surface, normal to the Mechanical strength IJ20, IJ22 plane of the
chip. Through Ink flow is through the High ink flow Requires bulk
Silverbrook, EP chip, chip, and ink drops are Suitable for silicon
etching 0771 658 A2 and forward ejected from the front pagewidth
print related patent (`up surface of the chip. heads applications
shooter`) High nozzle packing IJ04, IJ17, IJ18, density therefore
IJ24, IJ27-IJ45 low manufacturing cost Through Ink flow is through
the High ink flow Requires wafer IJ01, IJ03, IJ05, chip, chip, and
ink drops are Suitable for thinning IJ06, IJ07, IJ08, reverse
ejected from the rear pagewidth print Requires special IJ09, IJ10,
IJ13, (`down surface of the chip. heads handling during IJ14, IJ15,
IJ16, shooter`) High nozzle packing manufacture IJ19, IJ21, IJ23,
density therefore IJ25, IJ26 low manufacturing cost Through Ink
flow is through the Suitable for Pagewidth print Epson Stylus
actuator actuator, which is not piezoelectric print heads require
Tektronix hot melt fabricated as part of heads several thousand
piezoelectric ink jets the same substrate as connections to drive
the drive transistors. circuits Cannot be manufactured in standard
CMOS fabs Complex assembly required
INK TYPE Description Advantages Disadvantages Examples Aqueous,
Water based ink which Environmentally Slow drying Most existing ink
dye typically contains: friendly Corrosive jets water, dye,
surfactant, No odor Bleeds on paper All IJ series ink humectant,
and May jets biocide. strikethrough Silverbrook, EP Modern ink dyes
have Cockles paper 0771 658 A2 and high water-fastness, related
patent light fastness applications Aqueous, Water based ink which
Environmentally Slow drying IJ02, IJ04, IJ21, pigment typically
contains: friendly Corrosive IJ26, IJ27, IJ30 water, pigment, No
odor Pigment may Silverbrook, EP surfactant, humectant, Reduced
bleed clog nozzles 0771 658 A2 and and biocide. Reduced wicking
Pigment may related patent Pigments have an Reduced clog actuator
applications advantage in reduced strikethrough mechanisms
Piezoelectric ink- bleed, wicking and Cockles paper jets.
strikethrough. Thermal ink jets (with significant restrictions)
Methyl MEK is a highly Very fast drying Odorous All IJ series ink
Ethyl volatile solvent used Prints on various Flammable jets Ketone
for industrial printing substrates such as (MEK) on difficult
surfaces metals and plastics such as aluminum cans. Alcohol Alcohol
based inks Fast drying Slight odor All IJ series ink (ethanol, can
be used where the Operates at sub- Flammable jets 2-butanol,
printer must operate at freezing and others) temperatures below
temperatures the freezing point of Reduced paper water. An example
of cockle this is in-camera Low cost consumer photographic
printing. Phase The ink is solid at No drying time- High viscosity
Tektronix hot change room temperature, and ink instantly freezes
Printed ink melt piezoelectric (hot melt) is melted in the print on
the print medium typically has a ink jets head before jetting.
Almost any print `waxy` feel 1989 Nowak U.S. Hot melt inks are
medium can be used Printed pages Pat. No. 4,820,346 usually wax
based, No paper cockle may `block` All IJ series ink with a melting
point occurs Ink temperature jets around 80.degree. C. After No
wicking may be above the jetting the ink freezes occurs curie point
of almost instantly upon No bleed occurs permanent magnets
contacting the print No strikethrough Ink heaters medium or a
transfer occurs consume power roller. Long warm-up time Oil Oil
based inks are High solubility High viscosity: All IJ series ink
extensively used in medium for some this is a significant jets
offset printing. They dyes limitation for use in have advantages in
Does not cockle ink jets, which improved paper usually require a
characteristics on Does not wick low viscosity. Some paper
(especially no through paper short chain and wicking or cockle).
multi-branched oils Oil soluble dies and have a sufficiently
pigments are required. low viscosity. Slow drying Micro- A
microemulsion is a Stops ink bleed Viscosity higher All IJ series
ink emulsion stable, self forming High dye than water jets emulsion
of oil, water, solubility Cost is slightly and surfactant. The
Water, oil, and higher than water characteristic drop size
amphiphilic soluble based ink is less than 100 nm, dies can be used
High surfactant and is determined by Can stabilize concentration
the preferred curvature pigment required (around of the surfactant.
suspensions 5%)
* * * * *